Bank balance = QB register on 12/31/18 but gets screwed up at some point. I try to rebalance by going back Reconciling to this date/amount says "$2,113.02 Difference"

I'm here to help you fix your reconciliation discrepancy, Metro Management.

Edited or newly added transactions can cause a discrepancy in your previous reconciliation or balances. To isolate the issue, you can review the entries that affect the difference. Otherwise, you can undo the past reconciliation to fix the issue. You can also invite an accountant to your company to perform the process. An accountant can undo the entire reconciliation for you.

Here's how:

1. In QuickBooks Online Accountant, select the client from the drop-down list on the Toolbelt to open the client's company file.
2. Select the Gear icon on the Toolbar.
3. Under Tools, select Reconcile.
4. On the Reconcile an account page, select History by account.
5. On the History by account page, select the Account and Report period to locate the reconciliation to undo.
6. From the Action column drop-down list, select Undo.
7. When prompted to confirm, select Yes.
8. In the final confirmation window, select Undo.
9. Hit OK to confirm the action.

For more tips about undoing or redoing a reconciliation, you can open this article: Undo a client’s reconciliation in QuickBooks Online Accountant.

For more tips about fixing reconciliation issues in the future, you may follow the resolution provided in this link: Fix issues at the end of reconciliation in QuickBooks Online.

Let me know how else I can help you with your reconciliation by adding a comment below. I'm more than happy to help. Wishing you a good one!